Automatic stack type filter



Jan. 1, 1957 R055 AUTOMATIC STACK TYPE FILTER 2 Sheets-Sheet 1 Filed Jan. 14, 1955 INVENTOR; DELOSS H. ROBB "mama? ATTORNEY Jan. 1, 1957 D. H. ROBB AUTOMATIC STACK TYPE FILTER 2 Sheets-Sheet 2 Filed Jan. 14, 1955 INVENTOR. DELOSS H. ROBB TORNEY United States Patent 2,776,023 AUTOMATIC STACK TYPE FILTER Deloss H. Robb, Louisville Ky., as'signor to American Air Filter Co., Inc., Louisville, Ky., a corporation of Delaware Application January 14, 1955, Serial No. 481,943

7 Claims. (Cl. 183-52) This invention relates to stack type self cleaning filters, and in particular relates to improvements over the structure shown in Patent No. 2,220,347, issued November 5, 1940, to A. Nutting.

It is an object of the present invention to provide a stack type filter providing means to insure against the filter members becoming stuck or jammed during operation.

A further object is the provision of a stack type filter in which a spray of cleaning liquid is employedto cleanse the filter members.

Still another object is the provision of a stack type filter in which the filter members may be cleansed by a spray or bath of suitable liquid.

These and other objects will be apparent upon consideration of the following specification taken in connection with the accompanying drawings illustrating a preferr'edembodiment of the invention by way of example,

and wherein:

Figure 1 is a fragmentary side view in vertical section of the invention;

Figure 2 is a similar view of a detail; a

Figure 3 is a section taken on line IIIIII of Figure 2;

Figure 4 is a fragmentary sectional view of the lower half of Figure 1; and 7 Figures 5 and 6 are respectively side and rear elevation-a1 views of the drive mechanism.

Referring to the drawing, the filter apparatus comprises a housing having side panels 1, 1' on which are located endless guide tracks 2, 2 consisting of vertical runs joined at the top andbottom by arcuate track portions. A plurality of filter units 3a, 3b, 30 etc. each have stub shafts 4a, 4b extending laterally therefrominto the tracks 2, 2', and filter units 3b, 30, etc. form a stack resting upon a bottom filter unit 3a positioned horizontally at the bottom horizontal portion of the track in a bath 5 of cleaning fluid. Suitable sealing means 6, 6' are provided at the forward vertical edges of the stack, and the top and bottom of the stack are sealed by members 7, 8 secured in a channel strip. It will be understood that air to be filtered enters at the front and flows horizontally through the filter stack, exiting at the rear opening 9.

In this type of filter the bottom filter member 3a remains in its bottom horizontal position as shown, long enough to be cleaned in the bath 5 and the stack is advanced downwardly periodically while the bottom member 3a is being transferred to the top of the stack, and the member 3b then becomes the bottom member and assumes a horizontal position (replacing member 3a) to be cleaned. The mechanism for effecting this transfer will now be described.

At the top (Fig. 2) the guide members 10, 10' on wall 1 receive a slideable bearing member 11 which is bent over at the bottom at 12, and has a threaded stud 13 extending downwardly therefrom through an abutment bracket 14. A spring 15 is interposed between the bracket 14 and the bottom 12 around the stud, and a nut 16 on the end of the stud provides for adjusting the bearing member. A similar bearing member is similarly attached to wall 1' but is 2 not shown in detail, and a shaft 17 is journalled in the bearing members and carries a sprocket 18 at each end to rotate with the shaft.

At the bottom of the housing a shaft 19 is suitably journalled and carries spaced sprockets 21; and a pair of endless chains 22 extend around pairs of sprockets 18, 21. The resiliently mounted sprockets 18 at the top may be adjusted by nuts 16 to keep the chains under the proper tension. At one point on the chains adjacent links are each formed with projecting fingers 23, 24. It will be seen the chains are more remote from the front portions of the track than they are from the bottom, top and rear portions. As the fingers move along the bottom, the forward fingers 23 engage the forward stubs 4a of the bottom filter unit 3a, and as the fingers continue their travel around the lower sprockets 21 they move filter element 321 to the left (Fig. 1) from under the stack. As soon as the lower filter element 3a is drawn out from under the stack, the stack tends to drop and tends to push unit 3a ahead, but the second set of fingers 24 engages the rear stubs 4b to retard motion of the filter element 30. The fingers continue their travel, moving the filter element up the rear portions of the tracks and around the top, and disengage from the filter element just before this element reaches the top of the stack, so as to allow the element to slide down onto the stack by its own Weight. The chain motion is stopped at some point after the fingers disengage the element but before they have moved around to the bottom again. It will be understood the chains are driven at suitable intervals determined by a timer, an automatic pressure differential responsive apparatus (not shown) or by any other means, and the chains periodi- I ca'lly move one or more complete rotations as required.

The stack is retardedfso that it doesnot drop abruptly, by means now to be described. A second shaft 25 is journalled in the frame and near its ends carries serrated wheels 26 so positioned that a stub shaft 4a or 4b can enter the spaces 27 between the serrations. Shaft 25 is connected to shaft 19 by a chain 27' and sprocket 28 including a conventional one way clutch 28, so that shaft 25 is not driven by chain 27, but when the filter stack, in dropping down, turns the sprockets 26, these sprockets and shaft 25 are prevented by the clutch 28' from turning faster than chain 27', so that the stack cannot move down any faster than allowed by rotating sprockets 26.

The side 1' of the housing supports a motor 29 which drives a gear reducer 31, which in turn drives a sprocket 32 on shaft 19. By driving the chain from shaft 19 instead of from the top shaft, cocking of the bottom filter member due to play in the chain, is eliminated. If desired, this drive structure may be positioned in the housing between walls 1, 1' above the bath.

. It will be seen that the forward section of the tracks in which the filter members form the stack, are sufficiently spaced from the chains so that as the fingers begin their downward movement at the top, they disengage the stubs and the transferred filter member is allowed to drop by its own weight onto the top of the stack. When the filter member 3a is released at the top of the stack, it is necessary that this member be positioned in the tracks 2, 2 without canting, because if canted the member may jamb and not align itself on the stack. The provision made for properly positioning the filter member comprises an arm 33 suitably clamped to shaft 17. Thus, when the bottom member 3a has been carried around to the top, the arm 33 engages the filter member when it is released by the fingers 23, 24, and pushes it into vertical position against guide 33' where it rests on the uppermost filter member 30. After the top filter member is thus positioned the chains stop with the fingers 23, 24, and arm 33 in some indeterminate position, ready for the next transferring operation. The structure shown in Figure 1 may be employed in connection with the bath 5 for washing the filter members, or may be employed with a spray or agitation for this purpose. The housing 34 for receiving the bath res-ts on a pan 35 to which it is removably secured in sealing relation thereto in any suitable manner. A pipe 36, which enters pan 35 in suitably sealed relation carries a plurality of upwardly directed nozzles 37, and an opening 38 in the bottom of housing 34 enables a spray of liquid discharged from nozzles 37, to reach the lower filter member 3a. By supplying a suitable liquid to the nozzles 37 the filter member may be washed by a spray, or, a static bath may be employed in housing 34 for washing the filter member. Or, if desired, the spray nozzles 37 may discharge liquid or air into the bath to agitate the bath.

The arrangement illustrated insures against cocking of the filter units at the bottom, by having the sprockets 26 secured to shaft 25 to rotate therewith, so that both ends of the filter unit must move in unison, and the arm 33 at the top insures against the top filter unit being jambed.

I claim as my invention:

1. In a stack type filter, the combination comprising: a housing providing an air passageway; endless tracks in said housing at the sides of said passageway, said tracks comprising vertical runs joined at the top by curved portions; a plurality of filter members guided by said tracks and forming a vertical stack across said passageway, with the bottom member of said stack resting on a horizontally disposed filter member; means operated periodically for transferring the horizontal member in said tracks to the curved portion of the tracks at the top of said stack; and a rotary arm located adjacent the top of said stack for engaging and biasing said transferred member in the curved portion of the tracks at the top of said stack into vertical alignment with the stack.

2. A stack type filter as specified in claim 1 wherein: said means for transferring the horizontal member comprises a shaft adjacent the top 'of the stack carrying an endless band, and said arm is secured to rotate with said shaft.

3. A stack type filter as specified in claim 1 wherein: said transfer means includes a rigidly mounted lower rotatable shaft carrying sprockets; an upper shaft mounted for vertical adjustment and carrying sprockets and said arm; and endless bands around said corresponding sprockets.

4. A stack type filter as specified in claim 3 having: means for driving said lower shaft.

5. A stack type filter as specified in claim 1 having: a shaft carrying a sprocket adjacent each end, said sprockets being adapted to be engaged by the respective ends of a common filter unit to compel the ends of the filter unit to move in unison; and means coupling said shaft to said transfer means including an overrunning clutch to prevent said shaft rotating faster than said transfer means.

6. In a stack type filter the combination comprising: a housing providing an air passageway with a bottom chamber adapted to contain a liquid; endless tracks in said housing at the sides of said passageway; a plurality of filter members guided by said tracks and forming a stack across said passageway with the bottom member of said stack resting on a horizontally disposed filter member in said bottom chamber; means for transferring the horizontal member to the top of said stack; a pan located beneath said bottom chamber; and upwardly directed spray means in said pan, said chamber having an opening in its bottom to admit the spray to the bottom filter member.

7. A filter as specified in cl'aim 6 wherein said pan is removably attached to said chamber.

References Cited in the file of this patent UNITED STATES PATENTS 

